Dogs are a great first line of defense strategy. Normally, they are pretty territorial.

A different tactic could be the non-lethal approach as shown on some TV program: get a can of Great Stuff expanding insulating foam and fire away. If you saw the show you know that us guys have a natural instinct to protect the twin sources of our lineage (as it were). Just aim low and fire away. The hands will drop to protect and get mucked up. You could, of course, aim at the face and see what happens there.

This method may need to tried out the next outing with the guys. Find the one who is being a bit of jerk. Tell him "Here, hold my beer..." or "Hey watch this!!..." Could be fun for you and everyone else, minus one.